Two Studies Provide Insight Into Cocaine Addiction
Treating a cocaine addiction is challenging because the rate of relapse is high. Often, those who enter treatment are not able to maintain abstinence once they leave treatment and are again exposed to the triggers that they associate with the drug.
Two new studies offer promising information for the treatment of cocaine addiction. In one study, supported by the National Institutes of health, scientists at the University of California-Irvine identified a blocking hormone effective with hunger that may also be used to limit the temptation to use cocaine.
The researchers, Shinjae Chung and Olivier Civelli, observed how the melanin-concentrating hormone (MCH) and dopamine react to the use of cocaine in an individual’s brain. The researchers found that when MCH was blocked, the person experienced a lessening in their craving for cocaine. Dopamine is a neurotransmitter that is central to the brain’s pleasure response.
This is the first research study to examine the role of MCH and dopamine in relation to cocaine addiction, as well as providing evidence that the reaction is occurring in the nucleus accumbens. The nucleum accumbens is the area of the brain that is responsible for processing pleasure as well as fear. It is also the region of the brain affected by addiction.
The researchers worked with animal models that had developed a cocaine craving to examine the levels of MCH and dopamine in the nucleum accumbens of the mice. After the scientists used a formula designed to block MCH, the mice did not exhibit a craving for cocaine. In addition, the researchers observed that mice that lacked certain key receptors for MCH were significantly less likely to exhibit cravings for the drug.
The second study was conducted by Dr. Marco Leyton of the Montreal Neurological Institute at McGill University and was featured in the May edition of Biological Psychiatry. Dr. Leyton and colleagues examined a link between the brain’s reward circuits and cocaine and individuals’ likelihood of developing an addiction.
Dopamine levels in the brain are important in how the brain processes the use of addictive drugs and the reward or pleasure experienced when using them. To observe the effects of cocaine on this region of the brain, the researchers recruited ten individuals who were not addicted to the drug to sniff cocaine on the first day of the study, followed by sniffing a placebo on the second day.
The researchers examined the effects on the brain using PET scans and also used blood tests, conducted both before as well as after the cocaine and placebo were used.
The researchers discovered that the activation of dopamine through cocaine use varied between the participants. Those who had used cocaine less previously had a lower release of dopamine, while those who had used more cocaine previously had a higher release of dopamine.
The results of the study indicate that there may be a connection between the reward-circuit response and the likelihood that a person may develop an addiction to the drug.
